Lock-out telephone system.



PATENTED APR, 24, 1906.

L. A. SCHMIDT. LOCK-OUT TELEPHONE SYSTEM.

APPLIOA'IION FILED AUG. 21,1905.

LOUIS A. SCHMIDT, OF CHICAGO, ILLINOIS.

LOCK-OUT TELEPHON E SYSTEM.

Specification of Letters Patent.

Patented April 24, 1906.

Application filed August 21,1905. Serial No- 274,980.

To all whom, it may concern;

Be it known that I, LOUIS A. SCHMIDT, a subject of the German Emperor, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Lock-Out Telephone Systems, of which the following is a specification.

My invention relates to lock-out telephone systems, and has for its salient object to provide a simple and efficient lock-out system whereby the conditioning of the instruments of one subscriber for transmission of a message to or through the central oflice automatically actuates means for preventing the conditioning of the instruments of any other subscriber upon the same line for connection with central. In general, I provide for the accomplishment of such results by providing, in conjunction with each subscribers set of a bridging system, a air of relays, one of which controls the brldging connections of the subscribers set and is responsive to ourrent-flow through the line beyond such subscribers set to open the brid e, and the other of which relays controls the ine beyond such subscribers set or station and is responsive to the flow of current through. the bridge of said station to open the line therebeyond.

In the drawing I have diagrammatically shown in a single figure an application of my invention in relation to such portions of an ordinary telephone system as are germane thereto.

In said drawing, 5 and 6 indicate the linewires, with which are associated, preferably in alternation at successive stations, the lock out relaysAand B and associated parts of the telephone sets. Save for this alternating arrangement the subscribers stations 1, 2, 3, and 4 are identical in their composition and arran ement, and I will therefore describe one of them only. At each station a line-wire (5 or 6) is led to a contact of the main or line-controllin relay A with which the armature a normally contacts, connection being established from said relay-armature through the relay-coils in suitable manner for the purline-wire.

poses to be described, the coils for this purpose being suitably connected with the same At each station is also provided a normally open bridging connection, one end whereof normally connects the subscribers hook-switch with the line throu h the armature and contact of bridge-reday B, and the other end whereof, normally disconnected from the first said end at the switchhook whenever the receiver is hung, is connected to the opposite side of the line. .Thus the continuity o the normal bridge connections,- closable at the switch-hook, is dependent upon thefunctional inactivity of its bridge-relay B, while the continuity of the line beyond any subscribers station is dependent on the functional inactivity of the main relay of such station.

The relays A and B are so associated that when the bridge connections of an subscrib ers set are closed by the remova of the receiver from its hook and current is sup plied to the line the main relay A is actuated to open the connection of its armature a with the contact 9, thereby opening the line beyond, while the relay B is permitted to remain in condition to permit contact of its armature b with its contact point, and the connection, further, is such that when the bridge connections of any subscriber more remote from the central station than the subscribers set nowin uestion is closed and current is supplied to t e line the main relay A of the subscriber intermediate the closed to open the line, while the bridge-relay of such intermediate subscriber is actuated to open its respective bridge connections.

arranging the relays for this urpose is as fol lows: The line-wire to be led to the relays'is divided, on the one hand, the circuit includin in series both coils b and b of the compound Wound brid e-relay B and one coil (1 of relay A and, on t 1e other hand, includin the remaining coil a of relay A, the two branches bein connected to form a continuous loop whic includes the two coils of the relay A and the two coils of the relay B. In the specific arrangement shown it is contemplated that the coils a and o of the magnet A be wound in opposite directions, one coil bein wound from right to left and the other woun from left to right. The same relative arrangement holds for coils b and b of relay B, and it will therefore be apparent that if current is passed through the coils of either relay in the same directionthat is, through both coils bridge and the central station is not actuated.

I have 7/ found that a simple and efiicient manner 'of' from the same end-the coils will magnetically neutralize each-other, in effect, upon the core or magnet, so that the ma net will remain magnetically neutral and t e armature unresponsive thereto.

With the arrangement shown to secure the desired magnetic effect upon the armatures of the relays the windings of each main relay A should be in parallel with the line-wire to which the relay is connected and arranged for series connection with the wire of the cor responding bridge, While the bridge-relay B is conversely arranged with its coils disposed for parallel connection in the bridge-wire and series connection in the line-wire. Specifically, 7 indicates a wire connected atone end between -the coils a and a of relay A and at its opposite end connected'to the armature a of saidv'.relay.,while'8 indicates a wire connected between the coils of relay B and to the armatureof said relay; The contact 9, with which armature a normally contacts, is connected directly'in the line, while the contact 10 for armature b is a partof' the bridge connection. Gtherwise stated, the main line and bridge divide at the commencement of what I have termed the loop, the coils a i and 12 being respectively in the line and bridge circuits, so that through them current iiows always in the same direction, while the coils a and b are connected in a shunt across .the line and bridge wires beyond coils a and 6 so that the directionyf current-flow therethrnugh de ends upon whether. current hthe line beyond the station or through the bridgeat the station, the direction reversin accordingly as the line beyond or bridge is closed.

The connection of the telephone set may be made in any. usual manner to. leave the bridge-wire normally open, in the specific arrangement shown by-wayof illustration the contact 10 being connected by wire 11 with the switch-hook 12. Theiupper contacts 13 and 14' have connection by wires 15 and 16' (including, respectively the primary and secondary windings-18 and- 19.01 the induction-coil I and the transmitter T and receiver B, respectively) with-the bridge wire 17, connected with the side-of the line oppo' site to that'with which the relays of the subscribers station are connected. The wire 16 is also shown as including acondenser CY and has tapped thereto the ground-wire 20,in

cord connections, J indicating the usual jack,

. having its contacts connected with there spective sides of the line, and P indicates the 1 plug, having its sleeve and tip connected, as 1 usual, with the respective sides of a central battery C B. Any usual means for enabling 1; the subscriber to call the central station and i the calling subscriber.

erases phone installation may of course be employed, but are not here illustrated.

In general the operation of my improved.

system will be as follows: Under normal con ditions the line is open at each subscribers station, there being no connection afforded at any point between the line-wires 5 :and 6. Ii" now a subscriber'say at station 3-'removes his receiver from its hook and the operator at central station, respo'ndin tothecall received through any convenientapparatus, (not shown,) plugs in at the 'j aok J, current flows from the central battery (QB? through the line -'wire 6 to thegrelays of the calling subscriber and there divides, one branch including in series coils a" aid 0, of the relay A and coil 6 of relayB and'the other branch includingcoil b 'and relay B and the circuit, thence continuing through the wire '8, armature I), contact. 10, Wire 11, switch-hooklZ, contacts 13 and 14,.and wires 15, 16, and 17 to the return-conductor 5. It will be ap arent under such conditions the current 0wing in series through the coils a a of relay A that is to say,- in opposite directions through-the oppositely-disposed windingsenergizes said relay and causes the magnet to attract its armature (1, thereby opening the line-circuitat con tact 9 beyond the bridge of On the other hand, current-flow through the relay B is in parallel through the coils b Zi -that. is to say, in like direction through the oppositely-disposed windings-so that said relay remains neutral and its armature in contact with the point 8.

Accordingly, the bridge of the calling subscriber remains closed. It will be seen, however, that at allvinte'rmediate stations between the station of the calling subscriber and the central office current flows through the relays A and B of said intermediate subscribers, the flow being, on the one hand,

through the windings b 'b of relay B in series and thence through winding 0/ of relay A, and on the other ,hand, through winding a? of re lay- A alone, the branches .joinin at-wire 7 and' 'the main circuit continuing ough armature a and contact 9. Thus the coils of relay Bbeingconnected in series the. cirwit and the. windings of relay A being con- IIO rig

nected therein parallel, the relay Bis energized and the relay A remains neutral. Acc'ordi-ngly, at these intermediate stations the bridge-lines are opened at the contact 10, whileflthe main line remains closed. It will be apparent now that if any subscriber beyond thestation of the calling subscriberattempts to getconnection withcentral or with the main llne he is prevented from so doing 'on account of the rupture of the main line at the station of'the calling subscriber, due to the energization of the main relay A'or' said calling subscriber, while all subscribers intermediate the calling subscriber and central station are prevented from obtaining connection with the line by the opening at their own stations of their bridge-lines at the point 10, due to the energization of the bridge-relayB. It will be apparent that changes might be made in the specific windin and arrangement of the relay-coils and lihe construct-ion details Without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent of the United States, is

1. In a telephone system, a central station, parallel conductors therefrom, a plurality of normally open telephone sets bridged between said conductors, and in association with each such set means for controlling the continuity of a conductor therebeyond comprising a relay having its normally open armaturearranged to control the continuity of the line, and having a windin in shunt between the said conductor and the bridge connections, whereby current flows therethrou h in one direction to cause the attraction of t e armature, and opening of the line therebeyond when the bridge is closed at such station, and in the other direction to leave the armature unattracted and the line closed when a circuit is completed at a point more remote from central station than such station referred to.

2. In a telephone system, a central source of current-supply, two conductors extending therefrom, a plurality of normally open'telephone sets bridged between said conductors, and in association with each set, means for controlling the continuity of the normal bridge connections of such set com rising a relay having itsarmature arrangec to control the bridge and to close the normal bridge connections, said relay having a winding in shunt between a line conductor at the bridge wherethrough current Hows in one direction to cause the attraction of the armature and the opening of the bridge when the line-circuit is con'ipleted beyond such station, and to leave said armature unattracted when the bridge at such station is closed.

In a telephone system, a central station, line conductors leading therefrom, a pluralit'y of normally open telephone sets bridged between. said conductors, and at each subscribcrs station means for controlling the continuity of the line beyond such station, and for controlling the continuity of the normal bridge connections of such station, such means comprising contact devices and relay- .coils, said relay-coils being connected in shunt across the line and bridge conductors so that current-flow therethrough is in one direction, proper to actuate the contact devices to 0 en the line and maintain the bridge closed w en the bridge at such station is closed, and so that current flow therethrough is in the opposite direction suitable to 0 en the bridge connection and maintain the linecontacts closed whenthe bridge at a station more remote from central is closed.

4. In a lockout telephone system, a line conductor, a return-conductor, at each of a plurality of subscribers stations a normally open bridge havin associated therewith a telephone set inclu ing means for closing the normal 0 ening of said bridge, a relay controlling t e continuity of the line be ond the bridge, having opposite coils in para lel in the line and in series in the bridge, and a bridge relay controlling the continuity of the normal bridge connections having 0 osing coils in series in the line and in paral e in the bridge;

5. In a telephone system, a central source of current-supply, line conductors extending therefrom, telephone sets at the respective subscribers stations, and means at each station for automatically opening the bridge when a station therebeyond is conditio ed for communication with central, and au o matically opening the line therebeyond when such station is conditioned for communication with central, such means at each station comprising two relays controlling resp ectivel the bridge and line connections, and eac having coils wound to substantially neutralize each other in magnetic effect when a talking-circuit is completed through the connections which it controls.

6. In a lock-out telephone system, parallel line conductors and bridge telephone instruments, and at each subscribers station a bridge-controlling relay and a line-control ling relay, each of said relays having two coils adapted when connected in parallel in a circuit to neutralize the relay-magnet, and when connected in series to energize the same, and each relay having also an armature connected to a point between the coils of the relay, said relay-coils being arranged in series in a loop connected at a proper -point with a line conductor, the contact of one relay-armature being also connected with the same line conductor, whereby the line-circuit is established through the armature of said relay, and the contact-point of'the armature of the remaining relay being connected through the telephone instruments with the opposite line conductor, whereby the bridgecircuit is established through the armature of said relay.

7 In a telephone system, a central station, line conductors ext-ending therefrom, normally open bridged telephone sets, and in conjunction with each set electromagnetic devices controlling the continuity of the bridge and line connections, such devices being wound and connected for the passage of current through coils thereof in one direction when the bridge connections of such statlons are closed, and for the passage of current to the magnetic conditions produced by our- 10 therethrough in the opposite direction when rent-fiow through the line" therebeyond to the bridge connections at a station more reopen the bridge.

mote than central are closed, a contact-beam- In testimony whereof I hereunto set my ing armature in the line arranged to respond hand in the presence of two Witnesses.

to the magnetic eonditions produced by our I LOUIS A. SCHMIDT. rent flowJhrough the bridge of such station In presence of to open the line therebeyond, and abontact- GEO. T. MAY, J12, bearing armature arranged to respond only GEORGE L. CHINDAHL. 

